Simulation error

rameezib · July 16, 2013, 04:59

Hi,
During the simulation of a stator-rotor problem solved using periodic boundary condition, I'm coming across an error that states as

A wall has been placed at portion(s) of an OUTLET
boundary condition (at 13.4% of the faces, 13.5% of the area)
to prevent fluid from flowing into the domain.
The boundary condition name is: S2 Outlet.
The fluid name is: Air Ideal Gas.
If this situation persists, consider switching
to an Opening type boundary condition instead.

What does it means? Does that going to effect my CFX results?

evcelica · July 16, 2013, 05:58

Thats pretty self explanatory, your outlet has areas of recirculation where air is trying to come back in and the program stops it by placing a temporary "wall" at those areas. It will most certainly affect your results. Extend your fluid volume further downstream (preferred) or consider an opening type boundary condition.

This shouldn't happen if you are using periodic boundary conditions, are you sure you set them up correctly, you shouldn't have an outlet.

rameezib · July 16, 2013, 12:37

Thanks, anyways the solution was not converging, so I'm really thankful for your valuable help. Could you please help me to set the outlet to open type boundary condition. I have not come across this as i choosed a closed fluid domain, so please tell me how to give the outlet open boundary condition

evcelica · July 16, 2013, 15:54

If you are using periodic conditions you shouldn't have an outlet, only a mesh connection at your periodic boundaries.

If you are not doing periodic, then just change the definition of that boundary conditions from "outlet" to "opening" in CFX Pre.

ghorrocks · July 16, 2013, 19:03

Can you post an image of what you are modelling?

July 16, 2013, 04:59	Simulation error	#1
rameezib New Member Rameez Join Date: May 2013 Posts: 19 Rep Power: 12	Hi, During the simulation of a stator-rotor problem solved using periodic boundary condition, I'm coming across an error that states as A wall has been placed at portion(s) of an OUTLET boundary condition (at 13.4% of the faces, 13.5% of the area) to prevent fluid from flowing into the domain. The boundary condition name is: S2 Outlet. The fluid name is: Air Ideal Gas. If this situation persists, consider switching to an Opening type boundary condition instead. What does it means? Does that going to effect my CFX results?

July 16, 2013, 05:58		#2
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,167 Rep Power: 23	Thats pretty self explanatory, your outlet has areas of recirculation where air is trying to come back in and the program stops it by placing a temporary "wall" at those areas. It will most certainly affect your results. Extend your fluid volume further downstream (preferred) or consider an opening type boundary condition. This shouldn't happen if you are using periodic boundary conditions, are you sure you set them up correctly, you shouldn't have an outlet. Last edited by evcelica; July 16, 2013 at 11:43.

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July 16, 2013, 12:37		#3
rameezib New Member Rameez Join Date: May 2013 Posts: 19 Rep Power: 12	Thanks, anyways the solution was not converging, so I'm really thankful for your valuable help. Could you please help me to set the outlet to open type boundary condition. I have not come across this as i choosed a closed fluid domain, so please tell me how to give the outlet open boundary condition

July 16, 2013, 15:54		#4
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,167 Rep Power: 23	If you are using periodic conditions you shouldn't have an outlet, only a mesh connection at your periodic boundaries. If you are not doing periodic, then just change the definition of that boundary conditions from "outlet" to "opening" in CFX Pre.

July 16, 2013, 19:03		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Can you post an image of what you are modelling?